In general terms, this invention relates to vehicle weight classification systems for classifying the weight of an occupant on a vehicle seat. More particularly, this invention relates to a signal processing system and method for handling weight information in a vehicle weight classification system.
Modern day vehicles typically include safety restraints to protect passengers and drivers during impact. Such restraints include seat belts and airbags, for example. It has recently become apparent that customized control of airbags is desirable. The owner of this application has developed a vehicle weight classification system that is useful for determining the size or weight of a seat occupant and controlling an airbag deployment responsive to that determination.
One of the challenges in designing a weight classification system is keeping the system simple and robust. For example, there are limited choices among sensor arrangements that will provide desired results over the life of a vehicle seat. Additionally, space constraints and economic considerations place limitations on the components to be included in such a system.
One particular challenge is presented in processing signals that are available from conventional-type sensors that provide signals indicative of the seat occupant's weight. In one example, strain gauge sensors are used in a vehicle seat. The strain gauge sensors provide electrical signals indicative of the weight on the seat. Typical strain gauge sensor output, however, is not readily usable by a microprocessor with out special modification. The sensor signals are typically too weak to be immediately recognized. Further, typical analog-to-digital converters provided on conventional microcontrollers do not have sufficient resolution capability to make an accurate enough weight determination.
This invention provides a solution that converts such sensor signal information into a useful form that is readily used within a single microcontroller that preferably is also responsible for other operations of the weight classification system.